scope:

This International Standard specifies two methods of determining free caustic alkali in commercial soaps, excluding compounded products: - Method A, ethanol method; - Method B, barium chloride method. Method A (ethanol method) should be applied only to sodium soaps of ordinary quality, as the presence of certain additives brings in sources of error. It is not applicable to potassium soaps, because of the solubility of potassium carbonate in ethanol. Method B (barium chloride method) should be applied to all soft potassium soaps or mixed sodium and potassium soaps. The application of this method to sodium soaps of ordinary quality, which usually do not contain sufficient quantities of free caustic alkali to be determined by this method, is not recommended.